Question about Brother MFC-8840D All-In-One Laser Printer

1 Answer

Fuser Gear Md No. LJ 7416

Hi Guys.

I was given  this all-in -one unit, "if you can fix it, it's yours" senario. I've pulled appart the fuser and found two problems. The LJ 7416 gear has snaped in three places (need a new one) and the gear that drives this gear is slightly worn on the edges (will this need to be replaced?)

How much for the LJ 7416

Thanks for your time guys.


Posted by on

  • Dal B Oct 28, 2007

    Thanks Soulvistor, best advice. I will do that. I also have the HP OJ G85 from new, only problem was scanner failure, after a good clean it's still going strong!

    Thanks again Dal B

  • david85 Dec 07, 2007


    I am having the same problem, but i don't know how to open up to get to the fuser, Is there anyway i can get a service manual or some advice. Thank first



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  • Brother Master
  • 1,113 Answers

You will need to purchase these gears from a brother dealer but I warn against just changing the gears you mention, fuser driver gear in printer frame will be ok unless chipped, but usally the big gear on the fuser goes as does a little white one next to it, and these are breaking becase the fuser is hard to turn, if you just change the gear, the fault will reappear after a little use, best bet is to replace fuser assy (approx $150)

Posted on Oct 27, 2007

  • Soulvisitor
    Soulvisitor Dec 08, 2007

    David.. face back of printer one screw centre, panel comes off, now door can come off then right and left rear cover screw off, the unswer fuser and unplug.

  • Soulvisitor
    Soulvisitor Dec 16, 2007

    parts LINK



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I am not clear as the whether you put the errant fuser in the machine that was working and put the good fuser in the bad one so now you have 2 that don't work. If that is the case it is possible that the bad fuser has taken out the good machine. There are resistance tests that should be run on the fuser to see if it is shorted out. If it does short out, you may need to replace an internal fuse or link on the board.

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Error 50.7 colour laserjet 6030

Its either the fuser flag or pressure switch would be my guess. Remember when troubleshooting something. KISs....Keep It Simple....its usually the easiest thing that fixed the problem. Replace the fuser then work out from there, especially since you have a spare machine to work from. Here is the Canon Service manual page on it. Good Luck!!
From the Canon Service Manual:
50.7 Fuser Error : Fuser has experience a pressure-release mechanism error

1) Reseat the following connectors: fuser motor, fuse-unit home-position, intermediate & the DC controller PCB
2) Test the Fuser Pressure-release sensor by performing the paper-path test or the manual sensor test

3) Check the sensor flag on the Fuser Pressure-release sensor. If the sensor flag is damaged, replace the fuser.
4) Check the inside gear on the product that drives the fuser
5) Perform the fuser motor & fuser pressure release motore components test.
6) Replace the fuser Motor
7) Replace the Fuser

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Your machine is in need of a new fuser unit. HP LaserJet 2400 Maintenance Kit Installation - Fuser (Part 1 of 2) Installing the fuser. Turn the power off and unplug the printer. Wait 20 minutes for the printer to cool.
Open the back door of the printer, using enough force that the door opens completely and the hinge locks disengage, as shown below.

2400_openbackdoor.jpg Remove the 2 screws circled in red below.

2400_removebackscrews.jpg Close the back door, and then flip the printer so that it rests on its face. 2400_closebackdoor.jpg 2400_flipprinter.jpg

Next swing open the paper guard which shields the back of Tray 2 when it is installed.


Looking inside the Tray 2 cavity, use a flatblade screwdriver to release the two tabs--one on each side of the rear cover.
2400_pryleft_backgate.jpg 2400_pryright_backgate.jpg

Next remove the rear cover from the printer by pulling down and away.


Fuser Installation Continued . . .
Pry the grey DIMM cover loose and remove it.


Use a small flatblade screwdriver to disengage the tab on the connector shown below and unplug the connector.


Next (on the right hand side) remove the small black plastic cover, located near the green fuser gear, which hides the other fuser wires.
2400_removewirecover1.jpg 2400_removewirecover2.jpg

Then unplug the two connectors shown below and free the yellow/white wire from its guide clasp.


Now remove the four screws holding the fuser in place (shown below).


Now remove the black plastic piece shown below, the duplexer inlet guide. Gently pry the tabs on both ends loose and slide/rotate the guide back towards the fuser to release it.
2400_removeduplexguide2.jpg 2400_removeduplexguide3.jpg

Now you can remove the fuser, just pull it straight out towards you. Don't install the new fuser until you've replaced the main motor gear, as shown below.

Replacing Fuser Drive Gear

With the fuser removed, look into the printer and locate the main fuser drive gear on the left side of the fuser cavity (gear circled in red below).


Use a flathead screwdriver to pry the gear's release tab and remove the gear by sliding it off its metal bar.

2400_gearreleasetab.jpg 2400_removegear.jpg

Slide the new gear onto the metal bar--make sure the gear's release tab faces outwards so it will be accessible again--and lock the gear firmly in place.

Now repeat the fuser removal process backwards as you install the New Fuser:

Insert the new fuser and replace the four fuser screws. Replace the black plastic duplexer inlet guide, making sure both tabs click in place. Re-plug the single connector on the left side, and the two connectors on the right side. Replace the wire cover on the right side. Reinstall the DIMM cover. Finally, replace the back cover with its screws.

This is a difficult installation which should be done by a technician. Good luck with it !

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Hi there, i have an hp 3500 printer. the fuser was ript appart and needed replacment.(the rol was broken on one side and was not burning the inkt on the paper anymore) i have got a new one, but keep...

50.9 error - Fuser Failure (Abnormally High
Temperature Sub Thermistor)
1. The connector between the fuser and
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Reseat the fuser. Check the connector J5013
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2. Short in the sub thermistor. Turn the
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I think you've some problems on the connectors, check the connections.
If you are able, replace the broken fuser roller from the old fuser with one from the new fuser.

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What are the procedures to replace the fuser on a LJ 2727 MFP?


The fuser might be very hot. After turning off the printer power, allow the fuser to cool for atleast 30 minutes.

1. Remove the rear output bin.
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  • Squeeze the hinge pin out of its mounting hole.
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2.Squeeze the blue fuser-release tabs.
3.Pull the fuser straight back and out of the printer.


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As you mentioned that the printer makes loud grinding noise or squeaking when page comes out than i feel this is the noise coming out due to faulty fuser.
I want to be sure so please open the rear bin and try to print if still noise comes than i m sure it is fuser.
If there are smudges on the printed page or if some film coating is coming out with printed page than fuser roller are physically damage.
However in this case i assume fuser is faulty.
If there opening the rear bin noise goes off than top output rollers are faulty.

Thanks and Regards
Neeraj Sharma

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ACC C8057A 4100-mk-c4110a-mini.jpg Maintenance Kit, Fuser, 110V, LJ 4100 LJ 4100 Series ACC C8057-67901 4100-mk-c4110a-mini.jpg Maintenance Kit, Fuser, 110V, LJ 4100 LJ 4100 Series ACC C8058A 4100-mk-c4110a-mini.jpg Maintenance Kit, Fuser, 220V, LJ 4100 LJ 4100 Series
Selected Item RG5-5069-000 See RG5-5069-090 Not Available 0
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HP LJ 4100 Fuserkit RG5-5069 HP

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Not too good news I'm afraid. It sound like the fuser gear has failed. Generally the fuser unit (hot section or hot rollers in the back) need to be replaced. Usually when the gear has worn or failed the fuser rollers are also worn and need to be replaced. The gear can be replaced seperately but is a very risky operation and usually results in parts in the fuser unit falling appart due to age and wear, so it is best done as a unit. If possible do not run the machine as it can cause damage to gears around the fuser unit. The best option is to find out how much a fuser unit and labour to fit would be at your local service centre.

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Yes one can replace it but it aint no easy job, entire frame needs to come apart, I always change the whole L frame, but gear is available, set aside half a day, take pics or purchase the service manual, it still takes me 40 mins to change a frame on one of these, and you will need to go that far then some to get to just the gear in frame..
7deadab.jpg Link to part number/price/purchase of fuser drive gear

Not such a easy job, you have been warned from one who knows OK

Good luck

Jan 09, 2008 | Brother MFC-8840D All-In-One Laser Printer

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